MHC class II-associated invariant chain (IPR022339)

Short name: MHC_II-assoc_invar_chain

Overlapping homologous superfamilies


Family relationships



The CD74 antigen (also known as H-2 class II histocompatibility antigen gamma chain, MHC class II-associated invariant chain, Ia antigen-associated invariant chain, or Ii) plays a key role in MHC class II antigen processing: it stabilises peptide-free class II alpha/beta heterodimers in a nonameric (alpha-beta-gamma)3 complex after their synthesis, and directs transport of the complex from the endoplasmic reticulum to compartments where peptide loading of class II takes place [PMID: 9843486].

CD74/Ii is a single-pass type II membrane protein containing a thyroglobulin type-1 domain. The structure of the trimeric domain of the MHC class II-associated chaperonin and targeting protein Ii has been determined by NMR [PMID: 9843486]. The molecule is cylindrical in shape and reveals conserved molecular surfaces that may mediate interactions between Ii and class II molecules [PMID: 9843486].

GO terms

Biological Process

GO:0019882 antigen processing and presentation

Molecular Function

GO:0042289 MHC class II protein binding

Cellular Component

GO:0016021 integral component of membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.